# CVE-2021-21419: python3-eventlet: Eventlet is a concurrent networking library for Python

CVE-2021-21419 is fixed in python3-eventlet on 1 platform by python3-eventlet 0.25.1-2ubuntu1.1 (version 0.25.1-2ubuntu1.1), released May 7, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-21419
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0179
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 7, 2021

## Description

Eventlet is a concurrent networking library for Python. A websocket peer may exhaust memory on Eventlet side by sending very large websocket frames. Malicious peer may exhaust memory on Eventlet side by sending highly compressed data frame. A patch in version 0.31.0 restricts websocket frame to reasonable limits. As a workaround, restricting memory usage via OS limits would help against overall machine exhaustion, but there is no workaround to protect Eventlet process.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python3-eventlet Ubuntu 20.04 LTS (focal) | 0.25.1-2ubuntu1.1 | [python3-eventlet 0.25.1-2ubuntu1.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-eventlet-0.25.1-2ubuntu1.1.md) | May 7, 2021 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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